spirocheticidal /ˌspaɪroʊˌkitɪˈsaɪdəl/ adjective1 •Killing spirochetes.Penicillin was found to be actively spirocheticidal in vitro against the Reiter, Kazan, Nichols, and Noguchi strains of so called S. pallida, and a strain of mouth spirochetes. — 1944 formsmore spirocheticidal · most spirocheticidal